feat: Add format instead of only prefix for labels

[tjdevries]

I wanted to be able to have closing labels do something like </ $NAME > (or at least play with the idea).

This change should be backwards compat with prefix

[tjdevries]

Although now I'm kind of thinking, what if you allowed a function to be passed that returned the virtual text chunk (so it could be text + highlights if you wanted to configure that. it would be basically just as easy to implement)

[akinsho]

@tjdevries thanks for the PR 🙌🏾 , I made a few comments, nothing major. Think we can get away with re-using some existing logic and doing a hard switch here vs. trying to maintain backward compat since this plugin likely doesn't have very many users atm.

Regarding the function option I agree it would be easy enough to add but I'd rather wait to see if enough people end up wanting that, it appears on almost every line so I don't think it needs to be very fancy.

[akinsho]

The config module actually already has a mechanism for deprecations, you just need to specify what the fallback key is and the message to show the user
https://github.com/akinsho/flutter-tools.nvim/blob/a2a67dae9ff43d95caddf4d68cf5afcd4cb9d65d/lua/flutter-tools/config.lua#L61

[akinsho]

I'd actually rather break this (mean as that sounds) whilst this plugin is still fairly small/doesn't have that many users so I can keep things as simple as possible. I think if the user has overridden prefix with the deprecation table it should warn them of the change and they can change their config

[tjdevries]

Well the thing I was thinking for the function was I kind of wanted to be able to do different highlights for the // at the beginning of the line and then something else for the actual closing label. So doing a function might just be easier to make that, rather than having some convluted mess of options.

[akinsho]

That's fair enough, in which case I'd rather approach this by leaving the existing option as is, and offering a second option which is a function that does what you describe.

I'd approach it this way because by far the majority of issues I've seen are from users who are just trying to get to grips with nvim/lua in the first place so I'd definitely rather there be a very simple option much like coc or vscode where all they have to do is change a string and a more advanced option using a lua function for people who want to do fancier things.